1. Field of the Invention
This invention relates to improvements in brake adjustment devices for locomotives and more particularly, but not by way of limitation, to a quick adjuster device for converting a double clasp-type brake assembly to a single brake shoe assembly.
2. Description of the Prior Art
Locomotives, and particularly diesel locomotives, are normally provided with friction type brake shoes engageable with the outer periphery of the locomotive wheels for slowing or braking the speed thereof. The braking apparatus may be of the type adapted to work with one brake shoe on each wheel, commonly known as single shoe brakes, or with two brake shoes on each wheel, commonly known as a double shoe or clasp-type brake. For many years, the diesel locomotives have used metallic brake shoes which are made from cast iron having certain other ingredients. The coefficient of friction of the metallic shoes when engaged with the steel wheels of the locomotives is such that it has been necessary to provide the locomotives with double shoe or clasp-type brakes in order to obtain a sufficient braking action.
Non-metallic materials have been developed, however, for use with brake shoes in lieu of the former cast iron materials, said new materials normally comprising a composition of rubber, asbestos, and other components. The brake shoes utilizing this non-metallic material have a much higher coefficient of friction when in engagement with the steel wheels than the cast iron shoes. As a result, the braking forces must be reduced to obtain the braking patterns obtained with the iron shoes.
The reduction in braking force may be obtained in many ways, such as by reducing the air pressure arriving at the braking cylinder, or altering the brake rigging leverage ratio. However, the most common manner in which the braking force is reduced has been to convert the double shoe or clasp-type braking system to a single shoe braking system. In order to accomplish this, it is the usual practice to remove the normal common connection between the two brake shoes and replace the connection with a new anchoring or fulcrum point for the remaining brake linkage. Such an anchoring or fulcrum point may be a bracket such as shown in the McLean U.S. Pat. No. 3,446,319, issued May 27, 1969, and entitled "Brake Rigging Modification for Composition Brake Shoes".
Other problems inherent to the single brake shoe system remain, however. For example, the brake shoe wears out relatively rapidly, and it becomes necessary to adjust the slack due to the wear thereon in order to maintain an efficient braking operation. The well-known screw type brake adjusters are not only expensive, but also require a great amount of time for adjusting the slack in the brake system and are particularly time consuming when it is necessary to replace worn brake shoes. Thus, it becomes readily apparent that slide-type brake adjusters, such as that shown in my prior issued patents, U.S. Pat. Nos. 3,613,840 issued Oct. 19, 1971; U.S. Pat. No. 3,752,269 issued Aug. 14, 1973; U.S. Pat. No. 3,835,969 issued Sept. 17, 1974, all entitled "Quick Slack Adjuster for Locomotive Brakes", and U.S. Pat. No. 3,902,577, issued Sept. 2, 1975, and entitled "Brake Adjuster for Locomotive Four Wheel Truck and Single Brake Shoe", would be advantageous for use in combination with a double shoe system which has been converted to a single brake system, but heretofore such a slide-type adjuster for the converted brake system has not been available.